Polarized electro-magnetic relays



March 3, 1959 F.- E. ROMMEL 2,875,398

POLARIZED EILECTRO-MAGNETIC RELAYS Filed June 6, 1955 3 Sheets-Sheet 1 I Inventor Ms. W dqmmzz Attorney March 1959 F. E. ROMMEL 2,876,39

POLARIZED ELECTRO-MAGNETIC RELAYS 3 SheetseSheet 2 Filed June 6, 1955 Inventor M 6. M

Attorney March 3, 1959 v F. E. ROMMEL 2,876,398

POLARIZED EILECTRO-MAGNETIC RELAYS Filed June 6, 1955 3 Sheets-Sheet 3 Inventor Mflw Mink Attorney POLARIZED ELECTRO-MAGNETIC RELAYS 7 Frederick Emil Rommel, West Dulwich, London, England, assignor to Telephone Manufacturing Co. Ltd., West Dulwich, London, England, a British company Application June 6, 1955, Serial No. 513,381

Claims priority, application Great Britain June 14, 1954 12 Claims. (Cl. 317-172) .for telegraph signalling and have had therefore substantially the same number of parts as the larger forms of relay. Necessarily, the use of a large number of component parts made to the fine degree of accuracy required for producing a uniform instrument and capable of stability in operation, involves considerable difficulties both in the actual manufacture and in the necessary inspection. The simplest and most accurate method of manufacturing individual component parts to accurate dimensions is by the grinding of surfaces in parallel planes but in the earlier forms of construction it has only been possible to apply that technique to a certain proportion of the parts concerned.

In these earlier forms of relay, it has been usual to employ a frame member of non-magnetic material to which the remaining parts such as the polarising magnets, polepieces and contacts are individually attached with the result that the production and assembly of such relays that accurately finished parts involve considerable labour and the finished assembly requires rigorous checking. Furthermore, in earlier small relays, the design required that the polarising magnets should be set with their longitudinal dimensions at right angles to the surface of the armature which again introduced a limitation in the degree of compactness obtainable.

A further matter which has introduced difficulties in the production of miniature relays is the usual two-point armature suspension which has been employed for the form of armature suspension employed is the most important single factor affecting the useful life of a relay, since the armature suspension has a direct bearing on the contact traveLthe relay bias and the stability both with respect to time and temperature. Therefore considerable attention has to be paid in the'inanufacture'of relays to the design and adjustment of'the highly intricate suspension to ensure that it is mechanically stable under all conditions and that the armature is accurately set relatively both to the magnetic air gaps and to the contact assembly. With a two-point su'spensio'mthe amount of adjustment permitted by the suspension itself is clearly limited and there-- causes serious problemsowing to the very fine limits nits? Stews P t 2 within which the dimensions ofthe parts have to'be cs tablished particularly as regards the armature suspension and this accordingly usually limits the range of appl ica-,. tion of such relays. In actual fact the effects of such dis; tortion can sometimes be avoided without affecting the stability of the relay by arranging for the distortion to occur in parts of which the dimensions are not critical, However, even with such precautions, the distortion due, to changes in temperature may have a long-termjdeleterious effect on the relay because of internal stresses and strains set up when parts of different materials are fixed together at more than one point.

It is the general object of the present invention to "avoid orat least reduce as much aspossible'the above im'ention ed drawbacks of existing forms of relays In particulanjthei invention'aims at reducing the necessary numberpfcoin f ponent parts in the construction of theirela'yand thereby reducing the manufacturing requirements Furthermore, the invention aims at providing a driving system for such, relays in which all the component parts, exceptforthean mature suspension and the securing means andthe actuat ing or signals winding can have their effective surfaces ground to their critical dimensions'with the same end in view.

With these objects in view according to the. present invention, the framework of the relay is a flat frame of non-magnetic material having spaced side members and which supports a flat armature, a signals magnetic struc-' ture with ilat pole-pieces, and flat polarising magnets; the. armature itself, the said pole-pieces, the polarising magnet and a spacing member for the pole-pieces, are all accurate- 1y finished with p'arellel surfaces enabling these compo nents to be mounted in sandwich fashion with the appropriate flat surfaces clamped in contact with each other. In one form, the non-magnetic frame also serves as the I spacing member for the pole pieces of the signals mag:

netic structure with the armature pivotally mountedin the aperture of the frame between its side members and, in this case, the air gaps on either side of the armature are determined by the thickness of the said frame. However, a separate spacing member for the pole-pieces may be provided consisting of a bar of electrically insulating material extending across the flat frame and secured to its side members. In either case, accurately finished flat inner surfaces of the pole-pieces are in contact with correspondingly finished surfaces on the spacing member and,

' for convenience, the polarising magnets consisting of a pair of flat permanent magnets, have accurately finished inner surfaces respectively bedded o'n corresponding fiat surfaces on the outsides of the said pole-pieces. The spacing member, the said pole-pieces of the signals magnetic, structure and the permanent magnets may then all be held rigidly together by means of a single clamping bolt pass; ing through them. Then, internal stresses such as" occur; when different materials are clamped together at more than one point and are subject to various changes intem. perature, are eliminated. The longitudinal axes of the armature and of the pole-pieces extend in the same direc{ tion in a common plane; the actuating or signals winding of the relay embraces a core forming part of its magnetic structure.

The relay may have a detachable contact assembly which may either be fastened to the other parts by the same bolt which clamps them together, or the contact assembly may be separate and detachably fastened to the driving mechanism by a further bolt and this latter arrangement affords a considerable simplification in the final assembly of the relay. Thus the invention provides a relay consisting of a number of self-contained sub-, assemblies which it is possible to fasten together by means ofasinglefixingbolb M It is preferred to suspend the armature with respect to the flat frame of non-magnetic material by a 3-point or 4-point suspension mounted on the opposite side members. of the. frame. or, again, the. armature-suspension may, 36.35 set. forth in patent. application 540,911, filed.

the suspension point or points on one side only and the. armature. may be tilted. about its axis of vibration by relative. adjustment of. the two suspension points onone side of the frame. Thus the armature can be set up with. respect to. the frame in a simple fashion and before the relay as a whole is. assembled. This setting may be. made so that. the air. gaps on. opposite sides of the armature] and between the. latter and the pole-pieces are made. precisely equal. It is. preferable to make the relay frame,the suspension members and. the fixing membersall ofthe same non-magnetic material so as to avoid any distortion of the armature with, respect to the frame upon change. in temperature. Finally, all. junctions between. unlike materials, such as between the pole-pieces and the spacing member, are made at a single fixing point only, inorder to avoid setting-up of internal strain within the parts, on change of temperature.

In order that the invention may be clearly understood and, readily. carried into effect, two examples of miniature polarised relay constructed in accordance with the invention willnow be described more fully with reference to the accompanying drawings,.in which:

Figure l is a side elevation of one simple form of therelay;

Figure 2 is. a perspective view of the non-magnetic frame with thearmature and its suspension in position;

Figure 3 is a section of a detail taken on the line III. III in Figure 2; while Figure 4'is a similarview of a small modification;

Figure .5 is a perspective view of a relay provided with asuspension system in accordance with patent application 540,911, filed October 17, 1955;

Figure 6 isa plan of the same; and

Figure 7'is a side elevation;

Figure 8is an enlarged plan showing the front end ofthe armature and its suspension with the upper permanent magnet and thecontact assembly removed;

Figure 9'is a vertical section taken on the line IX-IX in Figure 8; and

Figure 10 is anelevation corresponding to Figure 7, of the centralpart of therelay with portions removed to show the clamping of the parts.

Referring first to Figures 1 to 4, the armature 1 is a rectangular plate of soft magnetic material suspended on a strip suspension 2'on an axis transverse to the nonmagnetic'frame 3 so that the armature is balanced about the suspension 2 and lies inthe window or aperture in the rectangular frame 3. A pair of soft iron pole-pieces 4 lie in contact, with opposite ground faces of the frame 3 at one end of the latter, from which they project to the right in Figure l and are connected by a soft iron yoke 5." The actuating or signals winding 6 of the relay could embrace the yoke 5, but is shown as carried by the limb ofjtheupperrpole-piece 4 for the sake of compactness. The signals flux as shown by the dotted line 7, passes transversely across the right hand end of the armature 1 in,Figure-1 from the upper pole-piece 4 to the lower pole-piece and with the current in the winding 6 in one direction, flows in the. direction of the arrows.

A pair ofpermanent magnets 8, each lies with its inner ground face in contact with the outer surface of one of the pole-pieces 4 as seen'at 9, and the magnets 8 extend to theleft in Figure 1 just over the suspension of the armature l-where they are furnished with inwardly projecting fiuxconcentrators or pole-pieces 10 for the polarising flux. The magnets 8 have like poles at the polepieces 10 and if these are north poles, the flux leaving the pole-pieces 10 passes for some short distance in parallel along the armature 1 and emerges from both sides of the armature in the neighbourhood at which the signal flux crosses the armature. The two polarising flux paths are shown in chain lines at 11 and if the pole-pieces 10 are of north polarity, the flux flows in the direction shown by the arrows. Therefore, the magnetic circuit is a divided magnetic circuit as disclosed in U. S. Patents 1,826,990, 2,412,123 and 2,559,399. In the example shown in Figuresl to 4, a simple detachable contact assembly is employed according to patent application 492,155, filed March 4, 1955, and is secured by a single bolt 12 passing through a hole 13 in the left hand end of the non-magnetic frame 3. The inner movable spring contacts 14 of the assembly are actuated by a ball 15 of insulating material mounted in the armature so as to project equally on opposite sides. The armature 1 is shown with an aperture 16 passing through it, the only purpose of which is to compensate for the weight of the ball 15 so that the armature isbalanced about the suspension 2. The outer or static contact springs 17 are supported by insulatingspacers 18 from the inner contact springs 14. The latter are tensioned at their free ends against buffer blocks 19 which extend from the relay frame 3. The outer fixed contact springs 17 are electrically connected together by the bolt 12 the inner springs 14-being insulated. However, the contacts may be arranged to be adjusted as disclosed in patent application 500,171, filed April 8, 1955, now Patent No. 2,827,535, but the contact arrangement forms no part of the present invention.

The length of the air gaps on either side of the armature 1 may be precisely determined by grinding the armature land the frame 3 to the requisite thicknesses. The frame 3, pole-pieces 4 and magnets 8 are all held accurately in their positions by a single fixing bolt 20 which passes through a slot 21 in the right hand end of the frame 3 allowing for longitudinal adjustment of these parts with respect to the frame.

The transverse suspension spring for the armature 1 is rivetted to the surface of the armature at 22 (Figure 2) at its mid-width and on the transverse axis of balance of the armature. The suspension web'2 as shown, in addition to its transverse member, has side members 23 which lie along the side members 24 of the relay frame 3 and it will be seen from Figure 2 that in this case, the web 2 is of symmetrical H-form although it may be of a a symmetrical T-form with only one side member 23. The side members 23 are attached at their ends to the side members 24 of the relay frame 3 so that, as shown, theweb 2 of the H-form provides a 4-point suspension. All of the arms of the suspension web 2 are shown as reinforced by ribbing at 25 in order to prevent lateral displacement of the hinge without interfering. with the vibratory movement of the armature.

Inorder to-receive the side members 23 of the suspension web '2, the side members 24 of the relay frame Sarerecessedas seen in Figures 2, 3 and 4' to form platforms 26 for securing the side-members 23. The ends of the side members 23 can-be raised or lowered by means shown inFigures 3 and 4 and by means of these adjustments, the armature may be raised or-lowered bodily or tilted about the longitudinal axis of the armature.

In the arrangement shown in Figure 3, the side arms 23 of the-suspension web 2 are extended as seen at 27, and are turned around the-shanks of a pair of screws 28 threaded into the side member 24 of the frame 3. The ends 27 of the side members engage over a raised boss 29 at the middle of the platform 26 and hence the arm 23 is pressed resiliently against the inner side of the heads of each adjusting screw 28. Thus the armature can be adjusted by simple screwdriver adjustments'on the screws 28. By adjusting all four screws equally, the armature is raised or lowered bodily. By adjusting the two screws on one side only, the armature is rocked about its longitudinal axis and by adjusting the two left hand screws or the two right'hand screws 28 on opposite sides of the frame 3, the armature is adjusted about its axis of vibration. Obviously, instead of extending the resilient side .arms 23, a coil spring may be employed encircling each adjusting screw 28 to produce a similar result. Again, the adjusting screws 28 as shown in Figure 4, may each be threaded into a screw-threaded cylindrical plug 30 to which it clamps the side arm 23 of the web 2. Each of the plugs 30 is screw-threaded into the side member '24 of the frame 3 and can be adjusted from below by a screwdriver and adjustments made as described with reference to Figure 3. In any of these cases, the frame 3, the suspension web 2 and the adjusting screws 28, 30 are all made from the same non-magnetic material, such as phosphorbronze or beryllium copper, so that distortion in the relative positionsof the relay frame 3, the armature 1, due to change in temperature is avoided.

Turning now to Figures 5 to 10, the relay is again mounted on a frame plate 3 which, however, does not now act as the spacing member but instead a bar of nonmagnetic insulating material 31 extends across the frame 3 to which it is clamped by a pair of bolts 32. As seen in Figure 10, accurately finished inner surfaces of the pole-pieces 4 are bedded on to corresponding surfaces on the spacing bar 31 and again, a pair of permanent magnets 8 each having an accurately finished face on its inner surface resting on a flux concentrating disc 8A of soft iron which, in turn, rests on a corresponding accurately formed face on the outer surface of the respective pole-piece 4. These parts are clamped in position by a single central bolt 33. The actuating or signals Winding 6 is again shown as embracing a rearward extension of the upper pole-piece ,4, best seen in Figure 7. The signals flux shown by the dotted line 7 in Figure 10 and the polarising flux shown by the chain line 11 run in similar way to that shown in Figure 1. In this case, the lower permanent magnet 8, as seen in Figures 5 and 7, extends up between the side limbs 24 of the frame 3 and the armature 1 lies at a somewhat higher level, as seen in Figure 7. In this case, the armature 1 consists of two strips of soft magnetic material rivetted together and with the suspension strip 2 clamped between them. The result of this is that the armature 1 tapers somewhat as it extends between the pole-pieces 4 giving a shortened air gap and increased flux density at the right-hand tips of the pole-pieces 4. The right-hand end of th'e'armature as shown in Figure 8 is offset as seen at 1A, and near its end bears the actuating ball of insulating material. This ball actuates the upper and lower movable spring contacts of the contact assembly seen best on the righthand side of Figure 7. These movable contacts are carried on springs 45 which are bent over almost horizontally so that a certain amount of rubbing takes place when they strike the stationary contacts 46. The contact assembly is mounted on a plate of insulating material 34 by a screw 35 and the plate 34 is secured to the relay frame 3 by a screw 36. This contact assembly, however, as already mentioned, does not form part of the present invention.

The adjustable suspension to the armature is in accordance with patent application 540,911 mentioned above, and need only be briefly described here. However, the armature 1 has a straight suspension strip 2 seen most clearly in Figure 9, and the ends of the strip 2 are somewhat enlarged as shown at 37 and are perforated so as to fit over a shouldered bush 38 at each end. The bushes 38 are bored and the bores countersunk at their lower ends where they rest on the coned upper ends of a pair of studs 39 which are adjustably screw-threaded into the side limbs 24 of the relay frame 3. Each bush 38 is also engaged by a perforated arm 40 of a plate 41, the arms 40 resting respectively on top of the two ends of the suspension strip 2. The plate 41 is arranged to be tiltable about theconed upper ends of the studs 39 and for that purpose, a screw 42 is screw-threaded into the forward part of the relay frame 3 and the head of the screw 42 presses on the forward end of the plate 41 which has an aperture 43 through which the screw 42 can pass. It will be noted from Figure 8 that the screw 42 clears the armature 1. The arms 40 are pressed down on to the respective ends of the suspension strip 2 by two bearers or spring fingers 44 (Figures 5 and 7), the front ends of which press on the arms 40. The bearers 44 are each clamped at its rear end on top ofthe insulating bar 31 by the bolt 32.

Each stud 39 has a screw-driverslot at its lower end so that each can be screwed up or down in the side limbs 24 of the spacing frame 3. If one of thestuds 39 is adjusted more than the other, the armature 1 is tilted about its longitudinal axis. If the screw 42 is adjusted without altering the studs 39, the plate 41 is rocked about the tops of these studs and the armature is tilted about its axis of vibration. Finally, if the two studs 39 are adjusted by equal amounts and at the same time the screw 42 is adjusted to a suitable extent, the armature can be moved up or down bodily.

I claim:

- 1. A polarized electromagnetic relay comprising in combination, a flat frame of non-magnetic material presenting spaced side members, a spacing member consisting of a bar of non-magnetic material arranged transversely of said side members and being bedded on accurately finished surfaces on one side of the side members of said frame, a signals magnetic structure having flat pole-pieces having accurately finished parallel inner surfaces in contactwith corresponding accurately finished surfaces on opposite side faces of said spacing member, said pole-pieces being supported in spaced relation to provide a working-gap between them, a pair of flat polarizing magnets supported on said pole-pieces and being spaced apart to provide an air-gap between them, each magnet having an accurately surfaced flat portion bedded on a corresponding accurately surfaced flat portion of one of said pole-pieces of the signals magnetic structure, means for clamping together said spacing member, said polepieces-of the signals magnetic structure and said polarizing magnets, and a fiat vibratory armature pivotally mounted on the side members of said frame to be located within said air-gaps with its mid-plane. substantially parallel to the inner faces of the pole-pieces of said signals magnetic structure.

2. A polarized electromagnetic relay according to claim 1, wherein saidclamping means comprises a single bolt passing through said spacing member, the pole-pieces of the signals magnetic structure and the polarizing magnets.

I 3. A polarized electromagnetic relay-according to claim 1, wherein such armature is pivotally mounted in the space between the side members of said frame and the air-gaps on either side of the armature between the latter and the pole-pieces of said signals magnetic structure are determined by the thickness of said frame.

4. A polarized electromagnetic relay according to claim 1' and also comprising a contact structure mounted on a flat surface of said frame, said flat surface being co-planar with said accurately finished surfaces of said side members of said frame.

5. A polarized electromagnetic relay comprising in combination, a rigid frame formed of non-magnetic material and having a plurality of machined parallel surfaces, at signals magnetic structure having fiat pole-pieces with machined parallel surfaces respectively abutting two parallel machined surfaces on opposite faces of said frame and supporting said pole-pieces spaced apart to provide a working air-gap between them, a fiat vibratory armature extending into said working air-gap, a pivotal suspension system for said armature also mounted on said frame, a contact assembly mounted on one of said machined surfaces of said frame, two flat polarizing magnets arranged on opposite sides of said frame and mounted on the machined outer surfaces of said pole-pieces and extending beyond said pole-pieces to embrace said armature, and clamping means holding said magnets, said pole-pieces and said frame together as a sandwich.

6. An electromagnetic relay according to claim 5, also comprising an armature suspension including an elastic suspension strip presenting a pair of arms extending from opposite sides of said armature in opposite directions respectively to the side members of said frame and adjustable means carried by said side members and adjustably supporting said strip to provide a bodily adjustment of said armature into a plurality of parallel planes, to provide a tilting adjustment of said armature about its axis of vibration defined by said strip and a tilting adjustment of said armature about its longitudinal axis to enable said armature to be set centrally between and parallel to the faces of said pole-pieces forming the effective air-gap.

7. An electromagnetic relay according to claim 6, wherein said armature consists of a pair of strips of soft magnetic material having said suspension strip clamped between them, the armature thus tapering slightly towards each end so that its surfaces are slightly inclined to the facing surfaces of the pole-pieces of said signals magnetic structure.

8. An electromagnetic relay according to claim 6, wherein at least one of the arms of said suspension strip is formed with an extension lying at an angle to the axis of vibration of said armature, said extension being adjustably attached to one of the side members of said frame so as to be tiltably adjustable with respect to said side member.

9. A polarized electro-magnetic relay comprising a frame of non-magnetic material having a pair of spaced side members and a spacing member extending transversely between said spaced side members, a substantially fiat armature of soft magnetic material supported upon said frame and located mid-way between said side members, a signals magnetic structure having two limbs engaging opposite faces of said spacing member and presenting pole faces on opposite sides of said armature, a pair of polarizing magnets supported on the two limbs of said magnetic structure, said spacing member having accurately finished parallel surfaces over the areas engaged by said two limbs, and said two limbs and polarizing magnets having accurately finished fiat surfaces arranged parallel to one another, and clamping means holding said magnets, said limbs and said spacing member together as a sandwich.

10. In a polarized electromagnetic relay, the combination comprising a rigid non-magnetic spacer bar formed with fiat parallel surfaces on opposite faces, a signals magnetic structure having two limbs, each of said limbs having first and second flat parallel surfaces onopposite faces and being mounted with said first surface in face to face engagement with one of said flat surfaces of said bar, a pair of polarizing magnets, each of said magnets being'formed with a fiat surface mounted parallel and close to said second surface of one of said limbs, and a single bolt passing through said magnet, said limbs and said bar and holding them together as a sandwich.

11. A polarized electromagnetic relay comprising in combination a non-magnetic rigid frame, including spacedapart side members and a cross-piece extending between said members and formed with two machined parallel surfaces on opposite sides thereof, a signals magnetic structure having two fiat pole pieces each with first and second machined flat surfaces parallel to one another on opposite sides thereof, said pole pieces being held with their first flat surfaces in face to face engagement with the said surfaces of said cross-piece and extending away from and transverse to said cross-piece to form a working air-gap between themselves, a flat vibratory armature extending into said working air-gap, a pivotal suspension system carrying said armature and supported by said side members, two elongated polarizing magnets having machined fiat surfaces held parallel and close to the said second machined fiat surfaces of the said pole pieces, said magnets extending away from said cross-piece outside said signals magnetic structure and embracing said armature, and clamping means holding said magnets, said pole pieces and said cross-piece together as a sandwich.

12. An electromagnetic device comprising a frame formed of non-magnetic material and comprising a pair of parallel side members joined by a cross member, an elongated magnetic armature, a pair of resilient suspension arms attached to said armature at an intermediate point along its length and extending along an axis at right angles to the axis of said armature, means mounting said armature upon said side members for vibration about the axis of said resilient arms comprising adjustable means carried by said side members and adjustably supporting the ends of said resilient arms, said adjustable means including means for adjustably tilting the supported ends of said arms about the axis of said arms, and the adjustable means on said side members being independently adjustable whereby the axis of said arms may be tilted about an axis parallel with the axis of said armature.

References Cited in the file of this patent UNITED STATES PATENTS 1,333,247 Cummings Mar. 9, 1920 1,826,990 Carpenter Oct. 13, 1931 2,559,399 Carpenter July 3, 1951 FOREIGN PATENTS 619,546 Great Britain Mar. 10, 1949 144,478 Sweden Mar. 16, 1954 

